Complex Variations of the Sciatic Nerve Branch and Morphological Variation of the Piriformis Muscle: a Case Report

Abstract

The sciatic nerve (SN) is the largest peripheral nerve in the body and comes from nerve branches from L4 to S3. We observed a variation of two slips of the piriformis muscle (PM) and abnormal branching pattern of the sciatic nerve in the left gluteal region of an 84-year-old woman. The muscle belly of PM was divided into two parts, superior and inferior (sPM and iPM). The common fibular nerve (CFN) was divided into two nerve branches, major common fibular nerve (mCFN) and accessory common fibular nerve (aCFN), and then, the tibial nerve (TN) had one nerve branch. TN and aCFN exited below the iPM, and mCFN passed between the sPM and iPM. And then, CFN and TN were merged at the level of femur neck. Here, we introduced rare variation of the sciatic nerve and the piriformis muscle, and discussed its clinical and embryological significance.